Partial-turn inductor coil



March 30, 1954 EDWARDS 2,673,922

PARTIAL-TURN INDUCTOR COIL Filed April f7, 1951 Power Supply l5 Fig.2.

\HHII J 111 Power Supply WITNESSES: INVENTOR John M.Edwords.

Patented Mar. 30, 1954 PARTIAL-TURN INDUCTOR con.

John M. Edwards, Baltimore, Md., assignor to Westinghouse Electric Corporation, East Pitt's burgh, Pa., a corporation of Pennsylvania Application April .7, 1951, Serial No. 219,843

- 4- Claims.

My invention relates tothe heat treatment of particularly metallic objects and, more specifically, to a partiabturn inductor apparatus, and method for its use in such heat treatment.

In the treatment of particularly irregularly shaped workpieces, which cannot easily be passed through the conventionalJfull-turn coil, the prior art heating apparatus is not too satisfactory. One effort to overcome this has been the splitturn coil, which has ,two sections, one of'them being movable relative to the other such that the coil can. be opened and the workpiece inserted into the opening thereb'etween. The two coil sections are then.closed,.and the heating current applied to the workpiece. Thistype ofv splitturn coil has ,proven to be relatively expensive to. manufacturein that it is rather dillicult to construct. Also, it is subject tolthe objection that .the satisfactory concentration. of. heating power in arelatively narrow surfaceareaoflthe workpiece is rather impractical to accomplish- Accordingly, it is an objectof .mysinvention to provide a novel type of induction coil for the heat treatment of workpieces and, particularly, workpieces having irregularly shaped surfaces.

It isa further object of my invention to provide a coil for use with particularly irregularly shaped workpieces, which ,is relatively inexpene siveto manufacture and'the construction process therefor. is not too complicated.

It is a still further object of my invention to providea coil for especially the described type of induction-heating purposes, which allows relatively simple workpiece positioning relative thereto for the heat treatment of said workpiece.

It is another object of my invention toprovide an induction coil for the heat treatment of particularly' irregularly peripheral-shaped workpieces; said .0011 being capable ofieffectively concentrating the induced heat energy into a rel atively: narrow surface area of the workpiece.

It is still another object of my invention to provide an induction heating coil which hasno portion requiring movement thereof in the proc ess of, loading or unloading'irregularly' shaped workpieces relative thereto.

It is an additional object of my invention to provide a method for heating or hardening workpieces, which is .more satisfactory than prior art methods, particularly respecting workpieces having irregular surfaces.

It isstill an additional object of my invention to; provide a novel ,method for hardening-pare ticularly" workpieces: having irregularly; shaped:

surfaces, which includes cooling the surfacapor .2 tions of the workpiece, which it isdesired not be subjected to the hardening-treatment, concurrently with the application of heat energy.

It isa different object of my invention to provide a novel method for the scansion heating or hardening treatment of particularly workpieces having an irregularly shaped surface, which method provides forthepooling of those workpiece surfaces, which ar not desired tube heat treated, concurrently with the heating and/or hardening treatment of other surfaces of the workpiece.

In accordance witlrmy invention, I provide a partial-turn induction coil for the heat treatment of workpieces. This type of coil'is especially suitable for-workpieces having irregularly shaped surfaces, such'that the workpieces can not be threaded or'passed through the conventional full-turn type of induction coil. The'proposed heating coil, and apparatus comprises a first section made up in thevform of ear-partial turn coil, which'provides heat energy for only a portion of the radial surface of the workpiece, the complete radial surface being effectively heat treated'by'rotation of the workpiecerelative-to the coil or movement of the coil relative tothe workpiece such that the entireradial surface of the workpiecetis exposed to the heating influence of said partial-turn'coil. The'apparatus includes a second'section which comprises one-or more current-carrying members for conducting the heatingcurrent between the partial-turn section and the power supply generator. This second section is connected to one. end of th partialturn coil in 'a particular manner such that the resultant field of the current carried by it does not have any substantial heating effect upon thevsurfac'e of'the workpiece undergoing -treatment; e

The preferred formof "my heating apparatus comprises .a partial-turn coil consisting of approximately av semicircular turn made of square copper tubing, which is 'generaliy shaped and adaptedfcr close coupling to the workpiece surface to beheat treated. The second section of my heating apparatus comprises two parallelconnected return sections made of copper tubing, the latter return sections being so positioned relative to the surface of :the workpiece undergoing heat treatment that the current is returned to the power supply, with no workpiece heating effect by themagnetic fieldset up, by the current in'the-return sections. Y Y

For; the purpose :of' hardening; treatment of particularly workpieceshavingirregularly shaped" surfaces, a plurality of quenching means and a method of scansion hardening treatment of the workpieces are provided. The above-described coil and heating apparatus and the workpiece are first relatively positioned for the heat treatment of a chosen section of the workpiece surface. If desired, a first quench means is provided to apply a coolant to the main body of the workpiece or any surfaces which it is not desired be heated by the magnetic field of the partialturn coil. Depending upon the workpiece to be treated, the heating apparatus including the partial-tum coil can be left stationary relative to the workpiece surface, or the heating apparatus including the partial-turn coil and workpieces can be moved relative to each other at the initial stages of the treatment.

In the case of particularly shaft members having collars and/or shoulders, with journal sections therebetween, it is more desirable to allow the partial-turn coil to remain stationary in the initial treatment stages, and near the corner between the journal and collar portion. During such initial period, the first quench means can be applying a coolant to the main body of the shaft to prevent undesirable heating therein.

After a predetermined interval of time, the workpiece and partial-turn coil section can be moved relative to each other, such that the partial-turn coil starts to scan along the surface of the workpiece. A second quenching means can be employed at this time to apply a coolant for the desired hardening effect of the heated workpiece surface. At the end of such scansion operation and any desired delay or soak periods, a third quenching means can be employed, if desired, to apply a coolant to the heated surface. For example, the latter surface may be adjacent an irregularity in the workpiece surface, such as a collar, and at the corner which is formed between a journal section and such collar. The third quench means effectively quenches and thereby hardens the workpiece surface directly beneath the partial-turn coil.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be' understood from the following description of specific embodiments when read in connection with the accompanying drawing in which:

Figure 1 shows a side view of my heat treatment apparatus positioned relative to a vertically arranged workpiece surface for treatment thereof.

Figure 2 is a plan view, partially in section, of'my apparatus as shownin Fig. 1; the section being. taken perpendicular to the axis or the illustrated workpiece, and

v Figure 3 shows a sectional view or my heat treatment apparatus taken along line III-III of Figure 1.

The workpiece treatment apparatus shown in Figure 1 comprises a partial-turn coil member consisting of approximately a semicircular or arcuate section of about one-half of a conventional full-turn induction heating coil, said partial turn it! comprising square copper tubing and shaped to be positioned relative to the surface of a workpiece ll such that a close coupling is obtainable therebetween. A pair of parallelconnectedcurrent-return sections 12 and'l4fare shown connected to one end of the partial-turn section III, said parallel-connected currentreturn sections being adapted for connection to the opposite terminal of a power supply source than the terminal to which the other end of the partial-turn section III is electrically connected. 'The latter electrical connection from the parallel-connected current-return sections l2 and [4, if desired, can be through ground, as illustrated in Figure 1. The parallel-connected current-return sections l2 and H are made of copper tubing such that a. coolant, for example water, can be passed through the partial-turn coil ill and through the current-return sections I2 and H to effect the desired cooling of the heating apparatus. A pair of relatively insulated current conductors l6 and I8 is shown in Figure 1, connected respectively to one end of the partial-turn coil section 10 and connected to the parallel-connected current-return sections 12 and M to provide a complete circuit for the heating current.

The illustrated workpiece ll comprises a shaft member, having an irregularly shaped surface along its axial dimension, in the form of a shoulder member 20, a collar member 22 and a journal surface 24 therebetween, with particularly sharp corners between the journal surface 24 and both the collar and shoulder members 22 and 20.

The initial heating position of the partial-turn coil [0, for purposes of illustration, can be ad-. jacent the shoulder member 20, in position to heat the journal surface 24. near said shoulder member 20, and the corner therebetween. In actual practice the partial-turn coil 10 has been positioned approximately inch from the shoulder 20 in such location. During the heating operation, the partial-turn coil II) was subsequently moved relative to the journal surface 24 in a direction parallel to the axis of the shaft member comprising the illustrated workpiece II.

The scansion movement of the partial-turn coil 10 was then stopped, when it was approximately. inch from the collar member 22.

In Figure 2 is shown an end view of the workpiece li showing the partial-turn coil Ill positioned relative thereto for the heat treatment of.

the surface of the journal portion 24 of the workpiece H. Heating current supplied from the power supply I5 enters one end of the partialturn coil l0 through a first current conductor l6 and is returned from the other end of the partialturn coil If! by means of the parallel-connected pair of tubular current-return members I! and l4 to the second current conductor l8 and back 'to the power supply source 15 through a ground connection.

A first quench means 26 is shown for the purpose of cooling the shoulder .member 20 and main.

body of the workpiece l I during, particularly, the" initial stages of the treatment cycle. A second.

quench means 28 is shown for cooling the heated' surface of workpiece H following the movement of the partial-turn coil I0, and a third quench means 30 is shown for cooling the surface immediately adjacent and beneath the partial-turn coil Ill at, particularly, the termination of the heat treatment cycle.

In Figure 3 is illustrated the workpiece I showing the partial-turn coil ill in relative heating position and during its scansion movement respecting the journal surface 24 to be treated. The first quench means 26 is shown in position to direct a coolant upon the shoulder member 20, and main body of the workpiece II- to be treated] The second quench means 28 is shown directed toward the heated surface, of the journal section 24 of the workpiece, that has already been heated and is in the process of being quenched, after the passage of the partial-turn inductor coil l 0. The third quench means 30 is shown in a position to direct a coolant toward the surface of the journal section 25, which is immediately below and under the influence of the partial-turn inductor coil Ill, when it is desired that acoolant be so applied.

In the operation of the work treatment apparatus, and method of treatment therewith, described herein and in accordance with my invention, the partial-turn inductor coil I0 is first positioned adjacent the surface of th journal section 24 of the illustrated workpiece II, which is initially chosen as the surface of the journal section 24 adjacent the shoulder member 20.

It is to be understood by those skilled in the art that many types of workpieces can be either 4 heat treated or hardened by means of the de scribed apparatus and in accordance with my invention, and it need not have, in particular, collar or shoulder members thereon. It is to be further understood that the partial-turn coil Ill need not be scanned relative to the workpiece surface, and is suitable for the heat treatment of any given portion of the workpiece surface for heating and, if desired, hardening thereof by means of any of the illustrated quench means.

With the partial-turn inductor l0 positioned relative to the surface of the journal section 24 for the heat treatment of that surface immediately adjacent the shoulder member 20, heating current is applied to the partial-turn inductor ID. If desired, the partial-turn inductorv I0 is allowed to remain in a stationary position relative to the axial direction of the workpiece ll undergoing treatment. During the entire heat treatment operation, it is to be understood that the shaft member may be concurrently rotated at a desirable speed, such speed being determinable for every workpiece by experiment or in accordance with the well-known teachings of the prior art.

The first quench means 26 can be employed at least during the initial heating period to apply a coolant to the shoulder member and main body of the workpiece II, which it is desired be not heated by the induced current from the partial-turn inductor [0.

After a predetermined interval of time, such that the surface of the journal section 24 and corner thereof, adjacent the shoulder member 20, is heated to the desired extent, the partial turn inductor I0 is started on its scansion cycle in a direction away from the shoulder member 20. The rate of scansion of such partial-turn inductor i0 is determinable for each work-piece experimentally, or can be chosen in accordance with the known teachings of the prior art as understood by those skilled in this particular art. It is further to be understood that this scansion movement need not progress at a constant rate along the workpiece surface. After the partial-turn inductor member I0 has moved away from a given heated surface of the journal section 24, and a suitable delay period has been provided for purposes of any desired soaking or temperature leveling effects, the second quench means 28 is employed to apply a coolant to that heated surface and effect the desired hardening thereof. The partial-turn inductor member [0 through its movement cycle continues its scanning, followed in movement by at least the second quench means 28 such that the surface of the journal section 24 is heated by the partial-turn inductor member It and subsequently is quenched and thereby cooled to effect the desired hardening by the second quench means 28. When the partialturn inductor member ID reaches the end of its scansion cycle, such that the surface and corner of the journal section 24 immediately adjacent the collar member 22 has been heated to the desired extent, the third quench means 33 is employed to apply a coolant to that surface and corner, and effect the desired hardening thereof.

In practical operation, as the partial-turn inductor scanning movement progressed along the surface of the journal section 24, the surface for a short distance ahead of the inductor coil ill was heated by induced current from its magnetic field, and the scanning movement was terminated when the inductor coil It was approximately 3 2' inch from the collar member 22. Further, in practice, the heating current was applied to the partial-turn inductor member it for a short time interval after its scanning movement stopped to insure proper heat penetration into particularly the corner between the collar member 22 and the journal section 2d. After the latter time interval, the heating current was discontinued to the partial-turn inductor member l0, and the third quench means 30 was employed to apply a coolant for the adequate quenching of the surface of the journal section 24 in addition to the corner betwen the journal section 24 and the collar member 22.

With the illustrated workpiece i I comprising a shaft having a journal section 24 intermediate between a shoulder member 20 and a collar member 22, the described heating and hardening method provided a hardened case along the journal section 24 up to within about ,4 inch of both corners, respectively, the corner between the journal section 24 and the collar member 22 and the corner between the journal section 24 and the shoulder member 20. The journal section 24 had an outer diameter of inch with a 4 inch collar 22 and shoulder member 20. A ZO-kilowatt, 450-kilocycle power supply source was employed in the actual practice .of my invention.

While I have shown and described certain specific embodiments of my invenion, many modifications thereof are possible. For example, the inductor member [0 may have only one current-return section, in lieu of the parallelconnected current-return sections [2 and I4, as shown in Fig. 1 of the drawing. My invention, therefore, is not to be restricted, except as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. An inductor for heat treating a sectional area of an article, said inductor being adapted for carrying heating current from a suitable power supply source having a pair of terminals, said inductor comprising a first sector having an arcuate shape and an axis and having a pair of end portions, one of said end portions being adapted for connection to one of said terminals, said end portions having the greatest physical separation of any two portions of said first sector, and a second sector including at least one current-carrying branch, said branch including an arcuate shaped portion and being connected to the other one of said end portions, said branch being positioned in the same direction relative to said axis as said first sector and being so shaped and positioned relative to said first sector that the current carried by said branch of said second sector does not have any substantial heating effect on said sectional area.

2. The apparatus in accordance with. claim 1 in which the second sector includes at least a pair of parallel-connected branches, which are commonly connected to the same end of the first sector, with the common connection between the one end of the first sector and the parallel-connected branches positioned in a perpendicular manner to said end of the first sector at the' point of common connection therebetween.

3. An inductor for heat treating a sectional area of an article with high-frequency power from a suitable power supply source having a pair of output terminals, comprising a partialturn inductor member having an axis and having a pair of ends with one end connected to one terminal of said power supply source, a pair of parallel-connected current conductors, each of said conductors having a pair of ends, said parallel-connected current conductors respectively having one end commonly connected to the other end of said partial-turn inductor member in respectively a perpendicular relationship thereto and their opposite ends respectively connected to the other terminal of the power supply source, said pair of conductors including respectively a substantially arcuate shaped portion and being positioned on respectively the same side of said I axis as the partial-turn inductor member.

4. In apparatus for the hardening treatment of a sectional area of an article, a partial-turn inductor member having an axis and having a pair of ends, a first and a second current conductive member respectively having a pair or ends,

each of said current cenaucuv'e members" having one end connected to a; first end of said partialturn inductor member in respectively a perpendicular relationship thereto and a second end adapted for connection to one terminal of a suitable power supply source, said partial-turninductor' member having its second end adapted for connection to the other terminal of said power supply source, said partial-turn inductor member being adapted for relative movement respecting said sectional area to be hardened in a direction along an axis substantially perpendicular to a plane containing said partial-turn inductor member, with each of said current conductive members being positioned respectively in the same relative direction from said axis as the partial-turn inductor member. H a

JOHN M. EDWARDS.

References cited in the" me of this patent UNITED STATES PATENTS 

